Light pointers are devices that project a light beam onto a surface area to highlight an item of interest. Their use has become commonplace at meetings, lectures, conferences, and other venues where presentation materials are shown on a display screen. The presentation materials are typically projected from a computer onto the display screen using a projection device connected to the computer, such as a liquid crystal projector. A presenter may use a light pointer at any time during the presentation to draw attention to particular locations or items of interest shown on the display screen with a light spot that is visible to the audience.
Most common light pointers are handheld, pen-shaped devices that hold a battery set, a control circuit, a light source module and a lens. The light source module includes a light source, e.g., a laser or Light Emitting Diode (“LED”), for emitting light at a given wavelength, for example wavelengths corresponding to red, green, or blue light.
Light pointers may also include switches or buttons for enabling remote control of basic computer functions. For example, United States Patent Publication Number 2006/0197756 describes a light pointer with switches mounted thereon to enable remote initiation of various computer keyboard commands and/or pointing device (i.e., mouse, touch pad, track ball) operations, such as select, move, left click, right click and double click. The light pointer emits a light beam onto an image projected onto a display screen to produce a visible light spot superimposed on the image. The light spot functions as a control cursor for a presentation computer. A video camera in an image processor connected to the presentation computer is used to scan the image projected onto the screen. The image processor then analyzes the scanned image to identify the position of the control cursor (i.e., light spot) emitted by the light pointer. A user may direct the control cursor to a position in the screen and emulate position-dependent computer commands via the switches.
Light pointers may also include controllers and wireless modules for transmitting control signals to the presentation computer. In United States Patent Publication Number 2006/0227107, for example, a light pointer is provided with a wireless operation module for transmitting control signals to a presentation computer indicating the pressing of a given switch mounted on the light pointer. One switch may be used to transmit a page-up signal to the computer and another may be used to transmit a page-down signal to the computer. The page-up and page-down signals indicate to the computer that a new page of presentation material is to be displayed and projected onto the screen.
Light pointers may also be integrated with other devices. For example, a light pointer may be integrated into a wireless mouse, as described in U.S. Pat. No. 6,417,840. The integrated device is capable of selectively communicating control signals to a computer when operating as a mouse and transmitting a light beam to a projection screen when operating as a light pointer.
In addition, light pointers may be adapted to generate a modulated output that serves as a control signal for a projection system. In United States Patent Publication No. 2007/0030460, a light pointer has a modulated output that is used to provide commands to a projection system. The projection system has an image sensor integrated into it for detecting the position of light spots emitted by the light pointer. In one example, a user may press a button mounted on the light pointer to cause it to pulse at a given frequency. The pulsation indicates to the projection system that the light pointer position is to be monitored for a mouse “dragging” event until the user presses the button again to stop the pulsation. Different frequencies may be used to activate different mouse events.
These and other currently-available light pointers can only function as remote control devices with the use of mechanical buttons or switches. A user must manually operate the switches to control the presentation computer. This may be cumbersome and difficult to perform in practice as the user must change focus from giving the presentation to operating the switches. The switches may also be prone to error or fail entirely during a presentation.
Accordingly, it would be desirable to provide a light pointer apparatus that is capable of emulating a remote control device such as a wireless mouse without the use of manual switches. In particular, it would be desirable to provide a light pointer apparatus and method for tracking the position of a light pointer and using the position to control a presentation computer.